The present invention is directed to a radome for a range warning radar (RWR) in a motor vehicle, the radome having thin, radar-transparent metal layers deposited on the surface of the radome for visually adapting the radome to its surrounding motor vehicle surface.
It is generally known to cover RWRs with a radome that is integrated in the radiator grill of a motor vehicle, and, by metallically vapor depositing the radome material in a way that does not hinder the radar radiation, to give the observer the visual impression that the radiator grill of the motor vehicle is not interrupted by a radome.
This is accomplished, as is known, by using a partial vapor deposition and by structurally molding the radome material, adapting its form to the radiator grill (German Patent Application No. 198 19 709 A1). What is disadvantageous is the possibility of snow or ice forming on such radome surfaces, and thereby degrading the radar transparency.
A motor-vehicle radar system is also known from German Patent Application No. 196 44 164, in which a dielectric member (radome) is positioned in the ray path of the electromagnetic waves to protect from the influences of weather and to focus the radiation. To detect and remove dirt and coatings of ice, snow, and moisture that become deposited on the radome, the radome has a system of electrically conductive paths. They can be used to heat the radome from the inside of the RWRs.
An object of the present invention is to devise a radome having a predefined type of construction for a RWR in a motor vehicle, upon which layers of snow or ice are prevented from forming.
The present invention provides a radome for a range warning radar (RWR) in a motor vehicle having thin, radar-transparent metal layers deposited on the surface of the radome for visually adapting the radome to its surrounding motor vehicle surface. The thin metal layers (3) have an ohmic resistance, and an electric current source (4) for heating the radome injects an electric current into the metal layers (3) which flows laterally through the metal layers (3). Adjustable electrical resistors (7) are provided in the electric circuit for injecting current in order to compensate for differences in the ohmic resistances of the metal layers (3) caused by manufacturing.
Preferably, an automatically controlled electric switch (8), which is controlled as a function of the radome temperature, is provided for switching the heat on and off.
The metal layers (3) may be covered with a protective coating, which is radar-transparent and visually transparent, to protect against external corrosive and mechanical damages.
The protective layer may be a scratch-resistant lacquer or an SiO2 layer.
In accordance with the present invention, electrically heating the radome prevents the formation of snow or ice layers. The radome is heated by way of the vapor-deposited, decorative metals layers, which exhibit an ohmic resistance and, in response to an electric current being conducted through laterally, heat up and, thus, act as electric heating conductors.
The approach suggested by the present invention makes it possible to prevent snow or ice from degrading RWR functioning. The outer appearance of a radome in accordance with the present invention can be adapted, as needed, to its ambient environment, so that it is excellently suited for installation in a motor vehicle surface with its special design requirements.